A psychiatrist who monitored him first said he suffered a psychotic episode in the attack – but later ruled he did not.

The judge said: ‘You were capable of manipulating the medical staff and influencing fellow patients; for example you knew which staff would accede to your demands for drugs and accused those who did not of being racist towards you.

‘You demonstrated violent and aggressive threats, even in that secure environment and at one point said that you aim to serve your sentence in bliss at Ravenswood rather than in prison.

‘At one stage you made a full confession to the crime, describing your anger towards Diana as being the motive.’

She added: ‘You planned the attack and concealed the knife nearby while you hung around all day for your target to appear. You plunged the knife into her back, narrowly missing vital organs.

‘Your intention was to kill her and it’s a matter of pure good fortune that you did not do so. Whilst the resultant physical harm caused is relatively minor, death was a distinct possibility.’

The knife was removed at Southampton General Hospital. Ms Pranskuniene said she fears going out and is worried whenever someone passes her home.

Mohammed tried to call his brother Hiwar Namiq the day before and was ‘angry’ that he did not answer his phone.

Members of the public Joe Cleall, Darren Shuker and Richard Evans helped chase Mohammed in Derby Road where the defendant said ‘I kill her, I kill her’ when asked why he stabbed her.

He poses a ‘very significant risk of serious harm’ to the public, his family and Ms Pranskuniene, the court heard.

He said ‘please’ as he was jailed but the judge said: ‘This isn’t a conversation.’

Pierce Power, for Mohammed, said the offence was ‘intrinsically linked’ to childhood trauma experienced in Iraq.

Det Supt Justin Norris said: ‘The members of the public in Portsmouth were brilliant, they really came together.

‘They went to her aid and having seen what happened, they chased him in order to make sure that he didn’t get away with what he had done, which was a brave thing to do.’